This invention relates to a locking collar for installation in a cylindrical cavity or a stuffing box of a rotary mechanical device, and more particularly to a two-piece collar to be placed in a cylindrical cavity, and to a method for installing the collar.
Rotary mechanical devices, such as mixers and centrifugal pumps, include an impeller mounted on a shaft which is driven by an electric motor. The shaft passes through a seal cavity or a stuffing box defined by a cylindrical cavity in the device housing. Typically, the shaft is supported by bearings at the motor end and seals are placed in the stuffing box to engage the shaft to prevent fluid from passing through the seal cavity and reaching the bearing and the motor to avoid causing damage to both.
In mechanical pumps, the seal cavity passes chemical fluids, solids, or solvents being pumped, many of which are corrosive or erosive. Accordingly, it is important that appropriate packing material is placed within the seal cavity. The end of the seal cavity is closed by a gland follower which can be adjusted axially to fix the position of mechanical seal elements.
Typically seal water is pumped into the seal cavity through a flush port (1) to prevent the fluid being pumped or mixed from traveling along the shaft to the bearings and motor and (2) to provide lubricant to the packing. It is desirable to prevent movement of seals or other mechanical elements about the shaft. Thus, it is highly desirable to provide a locking collar that prevents axial movement of these mechanical elements.
A suitable stuffing box with a bearing sealing element and system is described and claimed in U.S. Pat. No. 6,834,862 to Mark R. Wilkinson, the contents of which are incorporated by reference in their entirety. This patent describes a seal system including a bearing element with a bearing surface. This shaft sealing system works well, particularly when an additional bearing surface for the shaft is required. A rigid locking collar is desirable to fix the axial portion of the sealing elements.
While there are a wide variety of devices available for locking mechanical elements in place in rotary mechanical devices, it is desirable to provide an improved locking collar that can easily be installed in a seal cavity or stuffing box of such a device without the need to disassemble the device.